This invention relates to an analysis apparatus utilizing a fluorescent X-ray.
In an apparatus utilizing a fluorescent X-ray, if an X-ray illuminated to a sample partly goes off the sample, variation occurs in the fluorescent X-ray intensity obtained. In the case of conducting a quantitative analysis utilizing a magnitude in fluorescent X-ray intensity, in almost all cases the analysis value is an erroneous value.
FIG. 3 shows a conventional fluorescent X-ray analysis apparatus having an X-ray generating part 14 for illuminating an X-ray to a sample 20 disposed on a sample stage 19, a collimator 15 for collimating the X-ray illuminated to the sample 20, and an X-ray detecting part 16 for detecting a fluorescent X-ray generated from the sample 20. An imaging section 18 obtains a sample image of the X-ray illuminated to the sample 20 via a mirror 17. An image monitor section 21 receives the sample image from the imaging section 18. Utilizing a size-confirming division displayed on the image monitor section 21, it is possible to visually confirm whether the X-ray illuminated to the sample 20 is off the sample or not. Another conventional apparatus displays a region to be illuminated by the X-ray on the image monitor section 21. However, in this case confirmation of whether the X-ray illuminated to the sample 20 is off the sample or not is also made visually by a human who is operating the apparatus.
However, these apparatuses have a defect that no confirmation is possible whether the X-ray illuminated to a sample is not off the sample unless confirmation operation is made by a human. The recent analysis/measurement apparatus has reached the state that automation is necessary from the viewpoint of reducing personnel expenses and removing human error. A first problem is to automatically determine that the X-ray illuminated to a sample is not extended out of the sample.
The analysis apparatuses includes an apparatus provided with a plurality of collimators to restrict an X-ray. Where conducting a sample measurement, a collimator is selected matched to a shape or size of a sample by a human. A second problem is to automate this operation.
A third problem is, where determination is difficult by a monochromatic image, to extract a particular color and perform a determination process.
Where an analysis apparatus has being used for a long term or where environmental change such as temperature is severe, there is a fear that a center position in X-ray illumination deviates or X-ray illumination dimension changes. Due to this, when determining whether the X-ray illuminated to a sample is off or not, an X-ray illumination region is assumed a little greater than an actual size, whereby it is possible to cope with deviation in X-ray center axis and change in X-ray illumination range. Consequently, a fourth problem is to give margins to an X-ray illumination region individually in vertical direction and horizontal direction and solving the problem of X-ray extending out.
A fifth problem is to detect by what means whether an X-ray illuminated to a sample is extended out.
There is a situation that a smaller sample is to be measured than an X-ray illumination region. Accordingly, a sixth problem is to enable sample quantitative analysis even where determining that an X-ray illuminated to the sample is partly off the sample.
The present invention adopted the following means in order to solve the problems.
In a fine-part fluorescent X-ray apparatus having an X-ray generating part for illuminating an X-ray to a sample, an X-ray detecting part for detecting a fluorescent X-ray from the sample; a collimator part for restricting the X-ray illuminated to the sample, an imaging part for imaging a sample image, and an image processing part for image-processing an image imaged, as a former process a positional relationship is previously examined between a sample image to be acquired in the imaging part and an illumination region of an X-ray.
As process procedure 1 is acquired an image of the sample in a monochromatic image.
As process procedure 2 is extracted, in the acquired image of the sample, a coincident portion of the image with the X-ray illumination region by image processing means.
As process procedure 3 is examined a luminance change in the extracted image and, where there is a luminance change greater than a reference, determination is made that the X-ray illuminated to the sample is partly off the sample.
The apparatus is provided with a plurality of collimators to restrict the X-ray illuminated to the sample, repeatedly executes the determination process by the number of the collimators, and selects a collimator greatest in area among collimators that the X-ray is not off.
The image acquiring operation conducted in the process procedure 1 acquires the image of the sample in a color image, has means to extract a particular color from the acquired image and convert same into a monochromatic image, and can determine utilizing color information whether the X-ray illuminated to the sample is partly off the sample or not. A fluorescent X-ray analysis apparatus is thus structured.
The operation of extracting by an image processing means a coincident portion of an image with the X-ray illumination region conducted in the process procedure 2 can magnify information of the X-ray illumination region at arbitrary magnifications independently in vertical direction and horizontal direction to determine whether the X-ray illuminated to the sample is partly off the sample or not thereby giving a margin for axis deviation of X-ray illumination and change in illumination region.
As a first method of the process procedure 3, luminance change examination, a frequency distribution of luminance in the extracted image is calculated, a smoothing processing is made on frequency distribution data, the number of peaks concerning luminance is examined from a frequency distribution after smoothing.
It can be determined that the X-ray illuminated to the sample is partly off the sample where two or more peaks are found.
As a second method of the process procedure 3, luminance change examination, in the extracted image binarization is made with a designated threshold, and measurement is made on an area of pixels of a designated value of 1 or 0 after binarization.
It can be determined that the X-ray illuminated to the sample is partly off the sample where there is a significant difference between an area of an X-ray illumination range and an area measured.
As a third method of the process procedure 3, luminance change examination, an image luminance in the vicinity of the center of the X-ray illumination region is rendered as a reference luminance, measurement is made in the extracted image an area of pixels close to the reference luminance, and it can be determined whether the X-ray illuminated to the sample is partly off the sample or not, where there is a significant difference between an area of an X-ray illumination range and an area measured.
In the second and third methods of luminance change examination, it is determined whether the X-ray illuminated to the sample is partly off the sample or not, an area of a sample portion obtained by measurement is rendered as a sample area, the sample area is divided by the area of the X-ray illumination region to calculates a real illumination area ratio, an X-ray is illuminated to the sample in this state, a fluorescent X-ray intensity obtained in the X-ray detection part is divided by the real illumination area ratio thereby enabling estimation of a fluorescent X-ray intensity where the sample exists in the entire X-ray illumination region, and an estimated fluorescent X-ray intensity can be utilized for quantitative analysis.